The present invention relates to an image forming apparatus applied to a copying machine, a facsimile, a printer and the like, and more particularly, to an image forming apparatus controlling a toner flying from a toner carrier to a back surface electrode using toner passing control means controlled in response to an image signal, and applying the toner to image receiving means positioned between the toner passing control means and the back surface electrode, thereby forming images.
In recent years, with the improvements in the performance of personal computers and the development of the network technology, there has been a strong demand for printers or copiers having processing capability high enough for printing a large amount of documents and also color documents. However, such image forming apparatuses capable of outputting high quality monochrome or color documents at a satisfactory level and a high processing speed are much in demand and yet still under development.
As one such technique, an image forming technique according to so-called xe2x80x9ctoner jet (registered trademark)xe2x80x9d method is known. According to the method, a toner is let to fly onto image receiving means such as recording paper and an image carrying belt by the effect of an electric field for forming images.
The apparatuses disclosed by Japanese Patent Publication No. 44-26333, U.S. Pat. No. 3,689,935 (see Japanese Patent Publication No. 60-20747), and Japanese Patent Republication No. 9-500842 are known as the image forming apparatuses of this kind. The apparatus disclosed by Japanese Patent Application No. 10-100780 will be now described in conjunction with FIG. 6 by way of illustration.
In FIG. 6, a grounded toner carrier 31 carries and transports a charged toner, while a restriction blade 32 controls the toner on the toner carrier 31 into one to three layers and charges the toner. A supply roller 33 supplies the toner to the toner carrier 31 and charges the toner. Toner passing control means 34 is provided with a toner passing hole 35 around which a control electrode 36 is provided. A voltage corresponding to an image signal is applied to the control electrode 36 from a control power supply 37. Reference numeral 38 denotes a back surface electrode and 39 denotes a back surface electrode power supply. Reference numeral 40 denotes image receiving means such as recording paper transported on the back surface electrode 38.
In the above-described structure, as the supply roller 33 and the toner carrier 31 are operated to form an even toner layer on the toner carrier 31 with the restriction blade 32 and the toner layer is transported, a voltage is applied to the back surface electrode 38. Meanwhile, the image receiving means 40 is moved, and a voltage corresponding to an image signal is applied by the control power supply 37 such as a driving IC to the control electrode 36 in synchronization with the movement, so that the toner on the toner carrier 31 is allowed to pass the toner passing hole 35 and fly in response to the image signal and stick on the image receiving means 40. Thus, a desired image is formed on the image receiving means 40.
In order to form a fine image of 600 dpi (dots per inch) on the entire surface of the image receiving means 40, for example, the toner passing control means 34 must be provided with the toner passing holes 35 at such a pitch. Meanwhile, the holes inevitably cannot be arranged in a single row, and therefore as shown in FIG. 8, the toner passing holes 35 and the control electrodes 36 are arranged in a plurality of rows (eight rows in the figure). The toner passing hole 35 and the control electrode 36 are circular, and connection electrodes electrically connected to the control electrodes 36 are provided to extend on both sides in the moving direction of the toner carrier 31 in order to prevent mutual interference, and each connected to a lead in the driving IC outputting the control voltage.
Note that in FIG. 6, as an example of the constitution, the image receiving means 40 is composed of recording paper or the like, and an image is formed directly thereon, while the recording paper could vary in thickness, easily change in the property depending on the humidity, and easily deform during the transportation. In case of a color printer, the varying transportation of the recording paper makes it difficult to achieve synchronization in the timing of forming an image in each color, which could cause problems such as degradation in the image quality. Therefore, as disclosed by Japanese Patent Application No. 10-100780, an intermediate image carrying belt may preferably be used as the image receiving means 40 and the image formed on the image carrying belt may be transferred altogether onto recording paper in some cases.
The constitution above is now described in conjunction with FIG. 7. Reference numeral 43 denotes an endless type image carrying belt as the image receiving means 40, and the belt is made of a film produced by scattering a conductive filler within resin and having a resistance of about 1010Ùxc2x7cm, and wound around between a pair of rollers 44a and 44b. A pickup roller 45 feeds a recording paper sheet 46 on a one-sheet-basis from a paper feed tray, a timing roller 47 synchronizes the fed recording paper sheet 46 and the image position, and a transfer roller 48 transfers a toner image formed on the image carrying belt 43 onto the recording paper sheet 46. The transfer roller is pressed toward the roller 44a with the image carrying belt 43 interposed therebetween and applied with a transfer voltage. A fixing device 49 heats and presses the recording paper sheet 46 having the toner image transferred thereon for fixing the toner image on the recording paper sheet 46.
With the image forming apparatus of this kind, in order to form dots about as small as 100 xcexcm, for example, the small holes in the print head must be about as small as 100 xcexcm, so that the small holes could clogged up and resultant dots could be thinned or dots are not formed at all. This phenomenon occurs because in addition to the clogging of the small holes with dust scattered in the apparatus, the small holes may be clogged with a developer used for forming images as well. The deposited developer or foreign substances affect an electric field formed by the control electrode, or mechanically prevents the developer from passing, so that resultant dots are thinned or dots are not formed at all. Therefore, some cleaning means is necessary for the print head.
As conventional means for cleaning the small holes, there are a method of using an electric field or an air flow as well as a method of providing ultrasonic vibration to the print head which allows effective cleaning of a developer which is not charged or a developer solidified within the small holes for example as suggested by Japanese Patent Publication No. 3-57658.
According to the disclosure of Japanese Patent Publications No. 4-164659 and No. 5-77479, a developer passing control member having small holes and control electrodes is attached with a vibration generator providing vibration and the vibration forms an advancing wave propagating the developer passing control member so that all the small holes can evenly be cleaned. For the purpose, a vibrating member is secured along the row of small holes in the developer passing control member and a vibration generator is coupled to one end of the vibrating member.
Another conventional image forming apparatus employs a direct marking method according to which an image is directly formed on a recording member. An image forming apparatus disclosed by Japanese Patent Publication No. 44-26333 is a developer injection type apparatus according to one of such direct marking methods. According to the direct marking method, an image signal is input to a control electrode provided at a print head to cause an accelerated electric field, a charged developer is allowed to pass a small hole near the control electrode, and the developer is allowed to land on the recording member by a voltage applied to counter electrodes, so that an image is formed.
As an image forming apparatus of this kind, Japanese Patent Publication No. 9-30029 discloses an apparatus having a print head in which developer passing control means controlling passage of a developer through small holes is integrally secured to a supporting member and a driving IC for driving control electrodes is integrally provided to the developer passing control means.
According to the disclosure of Japanese Patent Publication No. 9-277583, one end of developer passing control means is secured to a developer storage container including developer carrying means, and the other end is attached as it is extended by an elastic member, so that the developer passing control means is integrally provided to a developer supply unit and the whole structure is detachably provided to the main body.
Meanwhile, in the image forming apparatuses having the above-described structures, the distance between the toner carrier 31 and the toner passing control means 34, in other words the distance between the toner carrier 31 and the control electrode 36 greatly affects the amount of the toner passed through the toner passing holes 35. Therefore, according to the disclosure of the Japanese Patent Republication No. 9-500842, for example, a scraper blade is provided between the toner carrier 31 and the toner passing control means 34 to maintain the distance. However, the toner layer on the toner carrier 31 is disturbed by a change in the contact pressure between the toner carrier 31 and the toner passing control means 34 caused by the eccentricity of the axial center of rotation of the toner carrier 31. Therefore, according to the disclosure of Japanese Patent Publication No. 8-118706, the toner passing control means 34 is secured through elastic securing means. However, the fluctuation of the toner passing control means 34 generated by the friction force at the contact point between the toner passing control means 34 and the moving toner carrier 31 causes the positional change of the toner passing hole 35, which disturbs the flying of the toner passed through the toner passing hole 35 and degrades the image quality.
Also, the toner passing control means 34 is made of several materials of different kinds, and therefore the tension corrugates the surface, and the distance between the toner carrier 31 and the toner passing control means 34 is unequal in the direction of the row of the toner passing holes, which degrades the image quality.
Besides, the toner passing control means 34 and the image receiving means 40 are positioned in the proximity at a distance in the range from 100 xcexcm to 500 xcexcm. Therefore, the toner on the toner carrier 31 passed through the toner passing hole 35 at the toner passing control means 34 in response to an image signal flies and sticks on the image receiving means 40 and then the toner returns from the image receiving means 40 to stick on the surface of the toner passing control means 34 and fall on the image, which degrades the image quality.
In addition, in the image forming apparatus having the above-described structure, the relative positions of the developer passing control member, and the vibrating member, and vibration generator must be fixedly set. Meanwhile, the gap between the developer carrying means supplying the developer to the small holes of the developer passing control member and the developer passing control member must be restricted highly precisely, or otherwise the magnitude of the accelerated electric field of the developer greatly varies, and high quality images cannot be formed. Therefore, the mutual positions of the developer carrying means and the developer passing control member at the time of the mounting operation of the developer carrying means and at the time of the axis fluctuation during the operation of the developer passing control member must be automatically adjusted. If the position of the developer passing control member is delicately adjusted in abutment against the developer carrying means, the rigidly provided vibration generator causes its relative position to the vibrating member on the developer passing control member to be incorrect, which impedes appropriate vibration propagation. As a result, the cleaning performance could not be achieved stably or correct images could not be formed by the distortion of the developer passing control member.
According to the disclosure of Japanese Patent Publication No. 9-30029, in order to maintain the attachment tolerance for the print head and the developer carrying means for forming high quality images highly precisely, they should be assembled integrally, which impedes simple supplement of the developer, in other words the device could be difficult to handle or maintain. If the integrated whole must be exchanged, the cost would increase, and the manufacturing and assembling could be complicated and the cost thereof could also increase.
According to the disclosure of the Japanese Patent Publication No. 9-277583, the developer supply unit having integrally formed developer passing control means needs only be exchanged and therefore the apparatus is easier to handle, but the high precision developer passing control means is included in the exchange unit, which pushes up the cost. Recycling of the exchange unit must be performed highly carefully, which eventually increases the cost.
The present invention is directed to the above-described conventional problems, and it is an object of the present invention to provide an image forming apparatus capable of forming high quality images by preventing the positional fluctuation of the toner passing holes, the corrugation of the toner passing control means, and toner flying and sticking to the image receiving means from returning from the image receiving means to stick and be deposited on the surface of the toner passing control means.
Furthermore, the present invention is directed to the above-described conventional problems, and it is another object of the present invention to provide an image forming apparatus capable of stably achieving cleaning performance according to a cleaning method by ultrasonic vibration and forming high quality images.
Still furthermore, the present invention is directed to the above-described conventional problems, and it is an object of the present invention to provide a low cost and easy-to-handle image forming apparatus which can form high quality images, can be easy to be maintained, and can be manufactured with high productivity, and to provide a manufacturing method and a manufacturing device therefor.
The first aspect of an image forming apparatus according to the present invention includes a toner carrier moving while carrying a charged toner, toner passing control means having a plurality of toner passing holes through which the toner passes and applying an image signal to a control electrode provided to surround the holes, thereby controlling passage of the toner, image receiving means to which the passed toner sticks, and a back surface electrode provided at the back surface of the image receiving means for drawing the toner. The toner passing control means is secured on the upstream side of the contact point with the toner carrier in the moving direction of the toner carrier, and is secured on the downstream side in the moving direction of the toner carrier through an elastic member. The upstream side is secured, so that the fluctuation of the toner passing control means caused by the friction force at the contact point between the toner passing control means and the moving toner carrier can be prevented, the positional fluctuation of the toner passing holes can be prevented and high quality images can be formed.
The second aspect of an image forming apparatus according to the present invention includes a toner carrier moving while carrying a charged toner, toner passing control means having a plurality of toner passing holes through which the toner passes and applying an image signal to a control electrode provided to surround the holes, thereby controlling passage of the toner, image receiving means to which the passed toner sticks, and a back surface electrode provided at the back surface of the image receiving means for drawing the toner. The toner passing control means is in contact with a stay extending in a direction perpendicular to the moving direction of the toner carrier on the downstream side of the contact point with the toner carrier in the moving direction of the toner carrier. The toner passing control means is contacted with the stay on the downstream side of the contact point with the toner carrier in the moving direction of the toner carrier, so that the corrugation deformation of the toner passing control means caused by applied tension can be prevented, the distance between the toner carrier and the toner passing control means can be constant in the direction of a toner passing hole row, which equalizes the toner amount passed through the toner passing holes, and high quality images can be formed.
The third aspect of an image forming apparatus according to the present invention includes a toner carrier moving while carrying a charged toner, toner passing control means having a plurality of toner passing holes through which the toner passes and applying an image signal to a control electrode provided to surround the holes, thereby controlling passage of the toner, image receiving means to which the passed toner sticks, and a back surface electrode provided at the back surface of the image receiving means for drawing the toner. The toner passing holes are contacted with the toner carrier through spacer means provided in a position on the toner passing control means on the upstream side of the toner passing holes in the moving direction of the toner carrier, the toner passing control means is contacted to a stay extending in a direction perpendicular to the moving direction of the toner carrier on the downstream side of the contact point with the toner carrier in the moving direction of the toner carrier.
Thus, the toner passing control means is contacted with the stay on the downstream side of the contact point with the toner carrier in the moving direction of the toner carrier, so that the corrugation deformation of the toner passing control means caused by tension applied upon the toner passing control means can be prevented. The spacer can be pressed evenly over to the toner carrier entirely in the direction of the toner passing hole row, so that generation of a space between the spacer and the toner carrier can be prevented, and the gap between the toner carrier and the toner passing control means can be constant and as thick as the spacer in the direction of the toner passing holes. Accordingly, the toner amount passing through each toner passing hole is equalized, and high quality images can be formed.
The fourth aspect of an image forming apparatus according to the present invention includes a toner carrier moving while carrying a charged toner, toner passing control means having a plurality of toner passing holes through which the toner passes and applying an image signal to a control electrode provided to surround the holes, thereby controlling passage of the toner, image receiving means to which the passed toner sticks, and a back surface placed provided at the back surface of the image receiving means for drawing the toner. There is a gap portion between the toner passing control means and the image receiving means gradually expanding toward the downstream side of the image receiving means from the toner passing holes. The toner from the toner carrier passed through the toner passing holes in the toner passing control means in response to an image signal and flying to arrive on the image receiving means can be prevented from returning from the image receiving means to the toner passing control means, so that spotless, high quality images can be formed.
Also, an image forming apparatus according to the present invention includes developer carrying means for carrying and transporting a charged developer, developer passing control means having a base member provided with a row of a plurality of small holes formed in the direction perpendicular to the direction of transporting the developer through which the developer passes and controlling passage of the developer through the small holes in response to an externally applied image signal, and image receiving means to which the developer passed through the small holes sticks. In the apparatus, a vibrating member is rigidly attached to a side portion of the base member of the developer passing control means in the arranging direction of the small holes, and ultrasonic vibration generating means for generating ultrasonic vibration is provided, and the ultrasonic vibration generating means and the vibrating member are coupled by coupling means allowing relative displacement between them and transmitting ultrasonic vibration.
Thus, ultrasonic vibration can be transmitted through the coupling means allowing relative displacement of the vibrating member secured to the base member of the developer passing control means and the ultrasonic vibration generating means, and the ultrasonic vibration can be transmitted if there is any fluctuation of the developer passing control means, so that stable cleaning performance as well as stable image formation can be achieved. Meanwhile, there is little possibility of distortion generated in the developer passing control means and therefore high quality images can be formed.
More specifically, the vibrating member may be provided with a coupling portion integrally extending toward the ultrasonic vibration generating means at one end, the coupling portion may have its tip end secured to the ultrasonic vibration generating means and a width-reduced portion may be provided in the coupling portion. Alternatively, a bent portion or a U-shaped portion may be provided in the coupling portion. As a result, the ultrasonic vibration can be transmitted while relative displacement is allowed in a simple structure.
The vibrating member may be rigidly attached to a side of the base member of the developer passing control means in the arranging direction of the small holes, ultrasonic vibration generating means for generating ultrasonic vibration may be provided, the vibrating member and the ultrasonic vibration generating means may be rigidly coupled and the ultrasonic vibration generating means may be supported in a displaceable manner. In this manner, the same function and effects can still be provided.
In particular, the developer passing control means has one end of the base member on the upstream side in the developer transporting direction, and the other end coupled to extension means, and the developer carrying means and the developer passing control means are partly in direct or indirect contact to set a gap between them. Application of this structure to the above described structure allows high quality images to be surely formed and stable cleaning performance can be achieved.
Conversely, the developer passing control means has one end of the base member secured on the downstream side in the transporting direction of the developer and the other end coupled to extension means, and the developer carrying means and the developer passing control means are partly in direct or indirect contact to set the gap between them. The above structure may be applied to provide similarly great effect.
The vibrating member is provided on the developer passing control means on the opposite side of a position where the developer carrying means and the developer passing control means are partly in direct or indirect contact in the direction of transporting the developer with reference to the small hole row. As a result, vibration by the vibrating member is surely transmitted to the small hole row in the developer passing control means, so that clogging can more surely be prevented. In this case, one end of the developer passing control means on the downstream side in the transporting direction of the developer is secured, and the vibrating member is provided between the secured end and the small hole row, so that the displacement of the vibrating member is reduced, and relative displacement of the ultrasonic vibration generating means and the vibrating member can readily be allowed. As a result, the above effects can surely be provided in a simple structure.
Also, the vibrating member is provided in a position on the downstream side of the arranging position of the small hole row in the developer passing control means in the direction of transporting the developer, and the base member of the developer passing control means is bent by the vibrating member. Then, the developer passing control means is bent and the member for preventing the corrugation can also serve as the vibrating member, so that the structure can be simplified while high cleaning performance can be achieved, and high quality images can be formed.
Further, the vibrating member is supported rotatably around the axial center, and the ultrasonic vibration generating means is supported pivotally around the axial center. As a result, the displacement of the developer passing control means can smoothly be absorbed by the rotation of the vibrating member, and ultrasonic vibration can be transmitted surely and effectively.
Besides, the vibrating member is rigidly attached to a side portion of the base member of the developer passing control means in the arranging direction of the small holes, while the vibrating member is supported rotatably around the axial center, and ultrasonic vibration generating means for generating ultrasonic vibration is provided. A coupling vibrating member rigidly coupled to the ultrasonic vibration generating means and the vibrating member are coupled in a relatively rotatable manner, so that the rotation of the vibrating member allows the displacement of the developer passing control means to be absorbed, and the ultrasonic vibration generating means can rigidly be provided. Therefore, the ultrasonic vibration generating means can be provided in a simple manner, while the displacement of the developer passing control means can smoothly be absorbed, and ultrasonic vibration can be transmitted surely and effectively.
Also in this structure, the developer passing control means has the base member having one end on the upstream side in the developer transporting direction secured and the other end coupled to extension means, and the base member of the developer passing control means is bent by the vibrating member. Thus, the structure may be simplified as described, while high cleaning performance can be achieved and high quality images can be formed.
In an image forming apparatus according to the present invention includes developer carrying means for carrying and transporting a charged developer, developer passing control means having a base member provided with a row of a plurality of small holes formed in the direction perpendicular to the direction of transporting the developer through which the developer passes and controlling passage of the developer through the small holes in response to an externally applied image signal, image receiving means to which the developer passed through the small holes sticks, and ultrasonic cleaning means for providing ultrasonic vibration to the developer passing control means, thereby cleaning the small holes, a seal blade is provided at a developer storing container wall or at a case wall storing a developer storing container, the seal blade has a tip end in contact with the inner surface in a position on the opposite side of a position where the developer carrying means and the developer passing control means are in direct or indirect contact in the direction of transporting the developer with reference to the small hole row in the developer passing control means. Thus, the developer passing control means is cleaned by applying ultrasonic vibration, while the vibration can prevent the developer from leaking to the outside along the inner surface of the developer passing control means.
An image forming apparatus according to the present invention includes developer carrying means for carrying and transporting a charged developer, developer passing control means having a base member provided with a row of a plurality of small holes through which the developer passes in the direction perpendicular to the direction of transporting the developer and controlling passage of the developer through the small holes in response to an externally applied image signal, image receiving means to which the developer passed through the small holes sticks, and a back surface electrode supporting the image receiving means and provided with a prescribed voltage for forming an electric field between the developer carrying means and itself to let the developer fly. The developer carrying means and a storing container storing a developer are integrated into a developer supply unit, and at least one end of the developer passing control means is positioned and secured to a box member having the detachably provided developer supply unit.
Thus, the developer passing control means can supplement a developer by removing the developer supply unit to the positioned and secured box member, which makes the apparatus easy to handle. The developer supply unit as a supply exchange part is not provided with the developer passing control means, which reduces the cost. The box member positions the developer supply unit and therefore high quality images can be formed.
One end of the developer passing control means is positioned and secured to the box member, and the other end of the developer passing control means is coupled to extension means. Thus, the developer passing control means may be displaced against the extension means for adjusting the position relative to the developer carrying means, the position of the small holes can be set precisely with reference to the one end, while the developer passing control means can be prevented from being loosened, and the developer passing control means can equally abut against the developer carrying means.
A guide shaft is provided to be projected at both ends of the developer supply unit, a guide groove with which the guide shaft engages when the developer supply unit inserted to the box member is provided, and the engagement of the guide shaft and the guide groove positions the small hole row in the developer passing control means and the developer carrying means in the plane direction perpendicular to the far-near direction of the axial center. By simply inserting the developer supply unit to the box member, the positioning in the plane direction can automatically be achieved.
The developer supply unit is provided with first spacer means for abutting against the back surface electrode and restricting the distance between the developer carrying means and the back surface electrode when the unit is mounted to the box member. In this structure, simply by inserting the developer supply unit to the box member and bringing the first spacer means into abutment against the back surface electrode, the gap between the developer carrying means and the back surface electrode can be highly precisely set to a prescribed distance.
Second spacer means is provided on the inner side of the developer passing control means, and said second spacer means abuts against the developer carrying means when the developer supply unit is mounted to the box member. The developer passing control means abuts through the second spacer means or directly against the developer carrying means when the developer supply unit is mounted to the box member, so that the developer passing control means is moved and the extension means is displaced. In this structure, simply by inserting the developer supply unit to the box member and bringing the developer carrying means into abutment against the second spacer means or the developer passing control means, the gap between the developer carrying means and the developer passing control means can be highly precisely set to a prescribed distance.
There may be provided means for pressing and urging the developer supply unit toward the back surface electrode and the developer passing control means as the developer supply unit is mounted. Thus, simply by mounting the developer supply unit, the distance between the developer carrying means and the back surface electrode, and the gap between the developer carrying means and the developer passing control means can be set highly precisely to a prescribed distance.
When the developer supply unit is mounted to the box member, the developer carrying means is in abutment in a position apart from a side edge of the upper surface of the second spacer means. Thus, developer carrying means can be prevented from colliding against the edge of the second spacer means and being damaged. The developer passing control means has one end detachably secured to the box member, so that the developer passing control means can readily be exchanged or maintained.
The developer supply unit has a protection cover for covering an exposed part of the developer carrying means when it is not mounted, so that the developer carrying means can surely be prevented from being damaged during the transportation of the developer supply unit.
The box member is detachably provided to a main body case. By removing the box member from the main body case, the maintenance of the developer passing control means such as exchange or cleaning or the maintenance of the back surface electrode or any intermediate belt used as image receiving means can be readily achieved.
The box member is provided with a mounting portion for a plurality of developer supply units and the developer passing control means parallel to each other, so that the developer passing control means and the developer supply unit can be positioned highly precisely parallel to each other by the single box member and high quality color images can be formed.
The developer passing control means can each be independently positioned, so that the small hole rows can be set highly precisely parallel to each other by individual adjustment of each developer passing control means. Misalignment among colors can surely be prevented and high quality color images can be formed and each developer passing control means can readily be exchanged and maintained.
When a plurality of developer supply units are mounted to the box member, the first spacer means provided to the developer supply unit abuts against the opposing back surface electrode, so that without the effect of fine distortion or curve in the box member if any, the distance between the developer carrying means and the back surface electrode can independently be restricted to the opposing back surface electrode highly precisely and stably for each developer supply unit. The recording conditions can be equalized for the plurality of developer supply units, and high quality color images in good color balance can be formed.
According to a method of manufacturing an image forming apparatus and a device therefor according to the present invention, the image forming apparatus includes developer carrying means and developer passing control means, a developer carrier is detachably mounted to a box member, one end of the developer passing control means is secured to the box member, and the other end is coupled to an extension member. The box member temporarily mounted with the developer passing control means is positioned and secured in a prescribed position, the developer carrying means or a dummy thereof is mounted in a prescribed position of the box member, and one end of the developer passing control means is held against the urging force of the extension member, while the position of the small hole row is recognize. The position of the small hole row is adjusted to be in a prescribed position, and one end of the developer passing control means is secured to the box member. Therefore, an image forming apparatus allowing high quality images by effectively and highly precisely positioning the developer passing control means can be manufactured with high productivity.